You've got a low 5 volts, and your Thermistors are old. What you're hearing is the normal boot-up sound. If it's doing it several times in a row, it means the voltage watchdog has caught the voltage at below 4.85 volts. WPC is notorious for low 5v stuff. You need to rebuild the 5v section. Usually just changing BR1 and BR2 on the power board does it for me, but the whole kit and kaboodle from plug on up needs to be looked at. When you get that multiple attempts to boot kind of thing, it also indicates that your thermistor is on the way out. It needs to "warm up" to start working. There's a board you can buy at kahr.us that should fix the problem, if you don't like soldering.

Edit: Pinwiki.com has a whole section on 5v problems on their site. It'll help tell you what to look at. Where ya operating out of, by the by?